System and method for extinguishing fire

ABSTRACT

A system and method for extinguishing fires is provided which includes applying an aqueous solution of a gel-forming material to structures in an area to be protected and separately applying an aqueous solution of a gel-inducing material to the same structures so that the solutions will mix and form a blanket of gas impervious aqueous gel which flowingly envelopes the structures and tends to smother any fire therein. The preferred gel-forming material is polyvinyl alcohol and the preferred gelinducing material is borax.

1 1 Sept. 3', 1974 United States Patent [1 1 Livingston 169/15Degginger......................... 169/14 X n a n a E U O D 00 2 677 WWWWWW 69 726 78 2 1 6 087 456 3 3 3 n O r a h S m w a F m D .w. m L m L. mMM m D H mm w U MG m mm m a t. SE .m M v 5 U U Primary Examiner-M,Henson Wood, Jr. Assistant Examiner--John J. Love Mass.

Attorney, Agent, or Firm-Lane, Aitken, Dunner & Ziems [73] Assignee:Factory Mutual Research Corporation, Norwood, Mass.

June 15, 1972 [22] Filed:

[57] ABSTRACT A system and method for extinguishing fires is pro- 21Appl. No.: 263,249

videdwhich includes applying an aqueous solution of a gel-formingmaterial to structures in an area to be protected and separatelyapplying an aqueous solution al to the same structures so [52] US.169/15, 169/16 [51] Int. A62c 35/00 [58] Field of Search.............169/1 A, 5, 13, 14, 15,

of a gel-inducing materi e 3 m o a 0. eb ke am e VJ me mm w mo fl nh .mh 'mw 14. 5 WW n mm ma mS SU em m MD. mm

References Cited UNITED STATES PATENTS structures and tends to smotherany fire therein. The referred gel-forming material is polyvinyl alcoholand P the preferred gel-inducing material is borax.

26 Claims, 4 Drawing Figures I e n r. e w

1,421,433 Epps 1,597,516 8/1926 Epps 2,580,011 12/1951 Freeman.3,198,258 8/1965 SYSTEM AND METHOD FOR EXTINGUISHING FIRE BACKGROUND OFTHE INVENTION This invention relates to a fire control and extinguishingsystem and method. More particularly, the invention is directed to asystem and method in which a substantially gas impervious blanket ofaqueous gel material is formed over objects in an area on fire andthereby create a relatively closed environment in which the fire will,in effect, be smothered and extinguished.

In relatively recent years a number of developments have occurred in thefire control art which involve the use of extinguishant other thanwater. For example, the use of foam blankets in fighting high energyfires, particularly fuel fires, is well known. In most cases foamblankets are applied from mobile units although the use of foam inconnection with fixed extinguishing systems is also known. While the useof foam has proved to be effective in areas where direct application toa fire is possible, it has limited usefulness in fighting fires inmaterials having large vertical surfaces, particularly in enclosed areasprotected by fixed extinguishing systems. In such cases, the systemoperates automatically and does not have the capabilities of applyingthe foam directly to the core" of the materials on fire. Thus, in awarehouse fire, for example, involving stacks or pallets of combustiblematerials, foam generated from a fixed system will perhaps coat the topportions of the materials and may even cover parts of the exposedvertical surfaces of the stacks. However, the foam will have no director indirect effect on the fire raging in the interior portions of thepallets and will thus often be ineffective in preventing destruction ofthe pallets. In addition, the fire may accelerate to the point whereeven the foam itself dissipates leaving the previously coated top andoutside vertical portions of the pallets exposed to the flames.

Of course, foam is not the only new development in fire control.Ablative water gels have been shown to be particularly effective infixed and mobile fire extinguishing systems. For example, in US. Pat.No. 3.605.900 entitled Method of Controlling Fire" issued to William L.Livingston and Russell W. Pierce and assigned to the assignee of thepresent invention, a method of fire protection is disclosed in which agelling agent in the form of a water-swellable polymer is injected intoa flowing stream of water supplying the sprinkler heads of a fixedextinguishing system upon actuation thereof to put out a fire in theenclosure protected by the system. By so introducing the gel into theflowing water stream. an ablative gel extinguish-ant is formed and isdischarged towards the fire. Since the gel enjoys a relatively highthermal absorption characteristic and a relatively high viscosity, arelatively low quantity of ablative extinguishant is required to put outthe fire, thereby enabling system designs with lower flow capacity, notto mention a significant reduction in water damage to the placeprotected. Also the gel tends to cling to the surfaces on which it issprayed to promote the smothering effect discussed above. While thismethod has proved to be extremely effective in fighting high energyfires, it does not fon'n a blanket" over vertical surfaces and therebyproduce a relatively closed environment in which a fire will besmothered.

SUMMARY OF INVENTION Accordingly, it is an object of the invention toprovide a system and method in which the combustible materials arecovered with a blanket of aqueous gel to assist in smothering, andtherefore extinguishing any fire within the materials.

Another object of the invention is the provision of a low cost systemand method for extinguishing a high energy fire by covering combustiblematerials in the area of the fire with a fire extinguishing blanketcomprising a substantially gas impervious aqueous gel.

It is a further object of this invention to provide a system and methodfor extinguishing fire in materials hav ing a relatively large verticalsurface area by forming an aqueous gel on the materials so that it flowsdown the vertical surfaces thereof forming an ablative, substantiallygas impervious blanket which is effective in smothering the fire.

The system which achieves these and other objects of the presentinvention features a plurality of discharge heads disposed in anelevated position in a space to be protected from fire, delivery meansfor separately de- BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is aperspective view of a building equipped with an automatic fixed fireprotection system of the present invention;

FIG. 2 is an enlarged sectional view taken along the line 22 of FIG. I;and

FIGS. 3 and 4 are views similar to FIG. 1, but depicting alternativeembodiments of the system of the pres ent invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG. I of thedrawings, a building I0 is shown in phantom lines which is equipped withan automatic fixed fire protection system embodying features of thepresent invention. In particular, the system comprises a buried feedmain 12 connected to a municipal water supply line I4 for deliveringwater to a piping system including a pair of parallel injector lines 16and 18, respectively, connected to a pair of risers 20 and 22. The feedmain 12 extends beyond the lines 16 and 18 and can be connected toinjector lines of other buildings or, in the case of a large building,to other injector lines of the same building. 7

A pair of injecting systems 24 and 25 are respectively connected to thelines 16 and I8 and are adapted to inject additives from storage tanks26 and 27 into the lines 16 and 18, respectively, as will be describedin detail later;

The risers 20 and 22 are connected to a pair of crossmains 28 and 30,respectively, which run for the length of the building 10 adjacent twoopposed walls thereof as shown. A plurality of spaced branch lines32-register with the crossmain 28, while a plurality of spaced branchlines 34 register with the crossmain 30, the branch lines 32 and 34being alternately disposed at equal distances apart, as shown. Thecrossmains 28 and 30, as well as the branch lines 32 and 34, may all besuspended from the ceiling of the building in a conventional manner.

A plurality of spaced direct discharge nozzles, shown in general by thereference numeral 36, depend from each of the branch lines 32 and 34,with the locations of the nozzles along each particular branch linebeing staggered with respect to the nozzles of its adjacent branchlines, as shown.

The injector systems 24 and 25 can be identical to the system disclosedin applicant's US? Pat. No. 3,642,072, issued Feb. 15, 1972, andassigned to the same assignee as the present application, with thedisclosure of the patent being hereby incorporated by reference. Ingeneral, the system includes a hydraulic motor driven by the watertapped at line pressure from the water conduits supplying the systemwhich, in the system of the present invention, would be the lines 16 and18. The motor drives an injection pump by which stored additive isintroduced into the flow lines in direct proportion to the water flowrate through the lines, with the increase of injection with increasingflow rates being terminated after a predetermined flow rate is attained.The system is controlled by a servo mechanism driven in part by a flowsensor in the water line to in sure injection rates corresponding to thewater flow. Since the specific details of the injector system are disclosed in the above patent, it is not shown, nor will be furtherdescribed, in any detail in the present application.

According to the present invention the additive stored in the tank 26and injected into the line 16 by the injector system 24 is a gel-formingmaterial preferably in the form of water-soluble polyvinyl alcohol,while the additive stored in the tank 27 and injected into the line I8by the injector system 26 is a gelinducing material, such as borax. Thespecific details of these materials will be discussed later.

The specific arrangement of the nozzles 36 are shown in FIG. 2. Inparticular three nozzles 36, one from a branch line 32 and two from theadjacent branch lines 34, are shown in an actuated. open condition inwhich they discharge extinguishant towards a supply of materials 40stored in the building 10.

The nozzles 36 can be identical to the nozzle disclosed and described incopending US. Pat. applica tion Ser. No. 160.7l5, filed July 8, 1971,and assigned to the same assignee as the present invention. thedisclosure of the application being hereby incorporated by reference.The nozzle is formed by a body member having an inlet for connection tothe branch lines and an outlet for discharging extinguishant. A closuremember normally closes the outlet to prevent the discharge ofextinguishant therefrom. The nozzle is opened in response to theexistence of both a predetermined fire condition, such as apredetermined temperature in the space to be protected, and apredetemiined condition .of the system, such as a predeterminedextinguishant pressure in the nozzle. In the event the nozzle is notopened despite the occurrence of the above-mentioned predeterminedtemperature, it may later be opened in response to the existence of botha second predetermined ftre condition, preferably in the form of anadditional predetermined temperature above the abovementionedpredetermined temperature, and a second predetermined condition of thesystem, preferably in the form of an additional pressure of the fluid inthe system lower than the above-mentioned fluid pressure. The nozzle canalso be opened in response to the existence of a third temperature inexcess of both of the abovementioned temperatures in the event it doesnot open under any of the above-mentioned conditions.

Since this nozzle is disclosed in complete detail in the above-mentionedapplication, it is not shown, nor will be described in any furtherdetail in the present application.

According to a preferred embodiment, the branch lines 32 and 34, as wellas the nozzles 36 on each branch line are spaced 10 feet apart. Also, asshown in FIG. 2, the spray pattern from each nozzle forms an angle ofapproximately 125. As a result, the gelforming solution from the nozzles36 on the branch lines 32 mixes with the gel-inducing catalyst solutionfrom the nozzles on the branch lines 34 in the general areas shown bythe letter X in FIG. 2 of the drawings.

It should be understood that the sizes of the conduits 28, 32 and 34, aswell as the nozzles 36 have been greatly exaggerated in FIG. 2 for theconvenience of presentation and that, in actual practice, thesecomponents will be much smaller in size relative to the dimensions ofthe building 10 and the materials 40.

The aqueous gel utilized in this invention must be capable ofsubstantially maintaining its integrity on vertical surfaces so that arelatively closed environment will be created in which a fire cannot besustained. The preferred material for forming such an aqueous gel iswater-soluble polyvinyl alcohol. When used in the context of thisinvention, the term polyvinyl alcohol should be taken as referring notonly to that substance as such but also including partially hydrolyzedpolyvinyl acetate. Polyvinyl alcohol and partially hydrolyzed polyvinylacetate may both be prepared by hydrolysis or alcoholysis of polyvinylacetate using alkaline or acid catalysts, but conversion of acetate tohydroxyl groups is essentially complete in the case of polyvinylalcohol. Commercial samples of partially hydrolyzed polyvinyl acetateusually correspond to -80 percent hydrolysis. Such samples and those ofpolyvinyl alcohol are both soluble in water, but the process ofdissolution and the variation of solubility with temperature differ inthe two cases. Polyvinyl alcohol is a light, white, powdery solid whenpure. It is soluble in water to viscous proportions but only when thewater is heated to a temperature above about C. 158 F.). Alternatively,it can be rendered soluble in water at room temperature by completelyglassifying it with plasticizing agents such as high molecular weightesters, dextrin and glycerol. However, since in most applicationsenvisioned by this invention, polyvinyl alcohol will be dissolved incold water, partially hydrolyzed polyvinyl acetate, or in other words,polyvinyl alcohol containing 20-40 percent acetate groups, is preferred.Such a substance dissolves readily in cold water and, as describedhereinafter, reacts favorably with a catalyzing agent to produce theintended gel. The polyvinyl alcohol may be stored in the tank 26 as anaqueous solution or a watermiscible organic solvent solution forsubsequent injection into the line 16. For convenience and economicreasons the aqueous solution is preferred. The concentration ofpolyvinyl alcohol in the stored solution is not critical but either theconcentration or injection rate must be adjusted so that when mixed withthe water in the line 16, it is present in a concentration of about 24percent by weight. Thus, the aqueous solution discharged from thenozzles 36 on the branch lines 32 will comprise about 2-4 percentpolyvinyl alcohol.

The catalyzing agent employed in this invention may be any water-solublesubstance capable of inducing the formation of an aqueous gel when mixedwith the gelforming material, particularly polyvinyl alcohol, describedabove. The preferred substance in this regard is borax, i.e., sodiumtetraborate lO-hydrate. This substance is a mineral obtained directlyfrom certain areas of the earth or it may also be prepared from kemite(Na B O '4H O). It is readily soluble in water and may be stored in thetank 27 as an aqueous solution. The amount of borax injected into thewater in the line 18 is not critical so long as it is sufficient to formthe intended gel. Thus, even the discharge of a saturated aqueous boraxsolution from nozzles 34 will cause the gel to form. However, in theusual case the concentra tion and/or injection rate of the stored boraxsolution will be such as to effect a discharge of a l2 percent by weightaqueous borax solution from nozzles 34.

The mixing of these two solutions will, for the most part, take place onthe surfaces of structures to which they have been applied. However,some preliminary mixing may take place in areas above the structures.These areas are designated in FIG. 2 by the letter X. As a result, ablanket of macrogel is formed on the surfaces of the stored materials 40which, for the purposes of this application, will be defined as aninfinite network structure of high molecular polymer chains which extendto its limiting boundaries. Two such blankets are shown by the referencenumerals 42 in FIG. 2. The macrogel thus formed is of a dilatant nature,that is, the viscosity thereof increases with corresponding increases inapplied molecular shear stress. In this respect. the macrogel behavesvery much like silly putty," a well-known composition sold commerciallyas a play-toy for children. Thus, the macrogel blankets 42 will exhibita plastic, or pseudoplastic flow and fall by gravity until they coverthe materials 40 in the manner shown in FIG. 2. Such blankets are gasimpervious and when exposed to thermal energy will form steam or watervapor. Also, since the gel does not have internal convection, it willshield the surrounding areas from thermal energy generated by the fire.Since the blankets are gas impervious and substantially envelop thematerials 40, they will tend to cause oxygen starvation of the fire.Furthermore, the fire itself will generate gases which, in the absenceof oxygen, will tend to smother the fire. As a result, the blankets 42not only extinguish the fire on the exposed surfaces of the materials,but they also smother any fire in the interior portions or core of thematerials.

After the fire has been extinguished, clean-up of the area may be easilyaccomplished since handling causes the macrogel to increase in viscosityto a point where it behaves like a rigid gel. Thus, it can be shoveledor otherwise picked up very easily.

Since the embodiments of FIGS. 3 and 4 are similar to that of FIGS. 1and 2, identical or substantially identical structure will be given thesame reference numbers. In the embodiment of FIG. 3, the risers 20 and22, and their corresponding crossmains 28 and 30, are disposed towardsthe center of the building and extend slightly abovetheir correspondingbranch lines 32 and 34, with the injector lines 16 and 18, the injectors24 and 25, and the storage tanks 26 and 27 being otherwise identical tothat of the embodiment of FIGS. 1 and 2.-

A plurality of vertically extending connecting conduits 29 connect thecrossmain 28 to its respective branch lines 32, and a plurality ofvertically extending connecting conduits 31 connect the crossmain 30 tothe branch lines 34.

A plurality of crosslines 35 connect adjacent pairs of branch lines 32and 34 at spaced intervals and are adapted to receive the heads 36.

The operation of the system of the embodiment of FIG. 3 is similar tothat of FIG. I in that occurrence of a tire condition in the building 10causes actuation of one or more of the heads 36, resulting in waterflowing from the line 14 through the main l2 and into the injector lines16 and I8. Polyvinyl alcohol from the tank 26 will be injected into theline 16 by the injector 24, while borax from the tank 27 will beinjected into the line 18 v by the injector 25. The resulting polyvinylalcohol solution and borax solution then flows through the risers 20 and22, the crossmains 28 and and the crossline, or crosslines,corresponding to the attached head, or heads, 36. The solutions will mixin each head 36 and form a blanket of macrogel which will discharge fromthe head toward the materials to flowingly envelop same as discussed inconnection with the previous embodiment.

In the embodiment of FIG. 4, a T-shaped coupling 19 is provided whichconnects each of the injector lines 16 and 18 to a single vertical riser21. Otherwise the injector lines 16 and 18, their correspondinginjectors 24 and 25, and the storage tanks 26 and 27 are identical tothose described in the previous embodiments.

The riser 21 is connected to a crossmain 29 which in turn is connectedto a plurality of laterally extending branch lines 31 which receive theheads 36.

A control device 38 is operatively connected between the injectors 24and 25 to insure that they will operate to selectively, intermittentlyinject polyvinyl alcohol from the storage tank 26 and borax from thestorage tank 27 into their respective lines 16 and 18 according to apredetermined cycle, in response to water flow through the lines as aresult of one or more heads 36 being actuated. Since the control device38 can be in any of a number of conventional forms, it is shown onlyschematically and will not be described in any further detail.

The polyvinyl alcohol and borax solution, as well as the pure water,will flow from the lines 16 and 18 into the riser 21 and crossmain 29for distribution to the actuated heads 36 via their respective branchlines 31.

Preferably the above-mentioned injection cycle is such that polyvinylalcohol will be injected into the line 16 for a predetermined periodsuch as 10 seconds, followed by a one second delay in which pure waterflows into the riser 21 from one or both of the lines 16 and 18,followed by a 10 second injection of borax into the line 18, followed byanother one second delay in which pure water flows into the riser 21,before the cycle is repeated.

In this manner each head will receive an intermittent injection ofpolyvinyl alcohol followed by an injection of borax, and the twosolutions will be discharged on top of each other near or at thematerials 40, whereby they will mix to form the blanket as discussed inconnection with the previous embodiments, which flow ingly envelops thematerials.

Although the disposition of the heads 36 in the embodiments of FIGS. 3and 4 is depicted as being similar to that of the embodiment of FIGS. 1and 2, it can be appreciated that the former disposition can be variedsomewhat as long as it is insured that all the materials stored in thebuilding will be enveloped by the blankets formed.

The above embodiments are to be considered in all respects asillustrative and not restrictive since the invention may be embodied inother specific forms without departing from its spirit or essentialcharacterisitcs. Therefore, the scope of the invention is indicated bythe claims rather than by the foregoing description, and all changeswhich come within the meaning and range of the equivalents of the claimsare intended to be embraced therein.

I claim:

I. A fire extinguishing system comprising a plurality of normally closeddischarge heads, conduit means supporting said heads in an elevatedposition in a space to be protected from fire, said conduit meansconnecting said heads to a source of water and comprising a first groupof spaced parallel branch conduits for receiving one group of heads anda second group of spaced parallel branch conduits for receiving anothergroup of heads, means associated with each head for opening said head inresponse to a predetermined fire condition in its vicinity to permitsaid water to flow through said conduit means for discharge from saidheads, delivery means responsive to said flow for separately deliveringan aqueous gel-forming substance to said first group of branch conduitsand an aqueous gel-inducing substance to said second group of branchconduits, said gelforming substance and said gel-inducing substancemixing with said water to form a solution of gel-forming substance and asolution of gel-inducing substance which are delivered to said one groupof heads and said other group of heads, respectively, said first andsecond groups of branch conduits extending in an alternatingrelationship along said space and the position of the heads on eachbranch conduit being staggered relative to the position of the heads onits adjacent conduits to mix said solutions upon their discharge fromsaid heads to form a fire extinguishing blanket of an aqueous gelmaterial for goods stored in said space.

2. The system of claim 1 wherein said means for opening said heads isadapted to open said heads in a manner to permit each head in said onegroup to discharge said aqueous gel-forming substance at the same time acorresponding head in said other group discharges said aqueousgel-inducing substance.

3. The system of claim 2 wherein said heads are adapted to dischargesaid substances in a divergent spray pattern, with the spray pattern ofeach head in said one group of heads adapted to overlap the spraypattern of a corresponding head in said other group of heads so thatsaid substances can mix at a predetermined vertical distance from saidheads to form said blanket.

4. The system of claim 3 further comprising means for separately storingsaid gel-forming substance and said gel-inducing substance, saiddelivery means further including means for separately releasing saidgelforrning and gel-inducing substances from said storage means to saidfirst group of branch conduits and to said second group of branchconduits, respectively.

5. The system of claim 4 wherein said conduit means further comprises afirst conduit connecting said source of water to said first group ofbranch conduits and a second conduit for connecting said source of waterto said second group of branch conduits, said releasing means furthercomprising means for injecting said gelforming substance and saidgel-inducing substance into water flowing in said first and secondconduits, respectively.

6. The system of claim 1 wherein said blanket flowingly envelopes saidgoods and substantially covers same.

7. The system of claim 1 wherein said gel-forming substance is polyvinylalcohol and said gel-inducing substance is borax.

8. A fire extinguishing system comprising a first group of spacedparallel conduits and a second group of spaced parallel conduitsextending in an alternating relationship in an elevated position in aspace to be protected from fire, means connecting said conduits to asource of water, a plurality of normally closed discharge headspositioned substantially intermediate two adjacent branch conduits andconnected thereto, means associated with each head for opening said headin response to a predetermined fire condition in its vicinity to permitsaid water to flow through said conduit means to said heads, deliverymeans responsive to said flow for separately delivering an aqueousgel-forming substance to said first group of conduits and an aqueousgel-inducing substance to said second group of conduits for mixture withsaid water to form a solution of gel-forming substance and a solution ofgel-inducing substance, respectively, for delivery to each of saidheads, said heads being constructed and arranged to mix said solutionsand discharge same in the form of a fire extinguishing blanket of anaqueous gel material towards goods stored in said space.

9. The system of claim 8 further comprising means for separately storingsaid gel-forming substance and said gel-inducing substance, saiddelivery means further including means for separately releasing saidgelforming and gel-inducing substances from said storage means to saidfirst group of spaced parallel conduits and said second group of spacedparallel conduits, respectively.

10. The system of claim 9 wherein said connecting means comprises afirst and second conduit respectively connecting said first and saidgroup of conduits to said source of water, said releasing means furthercomprising means for injecting additives into water flowing in saidfirst and second conduits to form said gel-forming substance andgel-inducing substance, respectively.

11. The system of claim 8 wherein said blanket flowingly envelopes saidgoods and substantially covers same.

12. The system of claim 8 wherein said gel-forming substance ispolyvinyl alcohol and said gel-inducing substance is borax.

13. A fire extinguishing system comprising a plurality of normallyclosed discharge heads disposed in an elevated position in a space to beprotected from fire, conduit means connecting said heads to a source ofwater, means associated with each head for opening said head in responseto a predetermined fire condition in its vicinity to permit said waterto flow through said conduit means to said heads, delivery meansresponsive to said flow for selectively and intermittently delivering anaqueous gel-forming substance and an aqueous gelinducing substance tosaid conduit means for mixture with said water to fomi a solution ofgel-forming substance and a solution of gel-inducing substance,respectively, for selective intermittent discharge from each of saidheads to form a fire extinguishing blanket of an aqueous gel materialover goods stored in said space.

14. The system of claim 12 wherein said conduit means comprises a riserconnected to said source of water, a plurality of branch conduitsconnected to said heads, and a cross-main conduit connecting said riserto said branch conduits.

15. The system of claim 12 further comprising separate storage means forsaid gel-forming and gelinducing substance, said delivery means beingadapted to selectively and intermittently release said gelforming andsaid gel-inducing substances from said separate sotrage means into saidwater flowing through said conduit means.

16. The system of claim 12 wherein said blanket fiowingly envelopes saidgoods and substantially covers same.

17. The system of claim 12 wherein said gel-forming substance ispolyvinyl alcohol and said gel-inducing substance is borax;

18. A method of fire protection comprising the steps of disposing afirst group of conduits and a second group of conduits in an alternatingrelationship in an elevated position in a space to be protected fromfire, connecting a first group of normally closed discharge heads tosaid first group of conduits, connecting a second group of normallyclosed discharge heads to said second group of conduits with theposition of the heads on each branch conduit being staggered relative tothe position of the heads on its adjacent conduits, connecting saidconduits to a source of water, selectively opening each head in responseto a predetermined fire condition in its vicinity to permit said waterto flow through said conduits for discharge from said heads, separatelydelivering an aqueous gel-forming substance to said first group ofconduits and an aqueous gel-inducing substance to said second group ofconduits in response to said flow, said gel-forming substance and saidgelinducing substance mixing with said water to form a solution ofgel-forming substance in said first group of conduits and a solution ofgel-inducing substance in said second group of conduits. which flows toand is discharged from said first group of heads and said second groupof heads, respectively, said solutions mixing upon their discharge fromsaid heads to form a fire extinguishing blanket of an aqueous gelmaterial for goods stored in said space.

19. The method of claim 18 wherein said heads are opened in a manner topermit each head in said one group to discharge said aqueous gel-formingsubstance at the same time a corresponding head in said other groupdischarges said aqueous gel-inducing substance.

20. The method of claim 19 wherein said heads are adapted to dischargesaid substances in a divergent spray pattern, with the spray pattern ofeach head in said one group of heads overlapping the spray pattern of acorresponding head in said other group of heads so that said substancescan mix at a predetermined vertical distance from said heads to formsaid blanket.

21. The method of claim 18 further comprising the step of separatelystoring said gel-forming substance and said gel-inducing substancebefore they are delivered to said first group of branch conduits andsaid second group of branch conduits, respectively.

22. A method of fire protection comprising the steps of supporting afirst and second group of conduits in an elevated position in a space tobe protected from fire with the conduits of the first group extending inan alternating relationship with the conduits of the second group,connecting said conduits to a source of water, connecting a plurality ofnormally closed discharge heads to said conduits with each head beingpositioned substantially intermediate two adjacent branch conduits andconnected thereto, selectively opening each head in response to apredetermined fire condition in its vicinity to permit said water toflow through said conduits to said heads, and separately delivering anaqueous gel-forming substance to said first group of conduits and anaqueous gel-inducing substance to said second group of conduits inresponse to said flow, said gel-forming substance and said gel-inducingsubstance mixing with said water to form a solution of gel-formingsubstance in said first group of conduits and solution of gel-inducingsubstance in said second group of conduits, said heads being constructedand arranged to mix said solutions and discharge same in the form of afire extinguishing blanket of an aqueous gel material for goods storedin said space.

23. The method of claim 22 further comprising the step of separatelystoring said gel-forming substance and said gel-inducing substancebefore they are delivered to said first group of branch conduits andsaid second group of branch conduits, respectively.

24. A method of fire protection comprising the steps of connecting agroup of normally closed discharge heads to a plurality of spacedparallel conduits, connecting said conduits to a source of water,selectively opening each head in response to a predetermined firecondition in its vicinity to permit said water to flow through saidconduits for discharge from said heads, and selectively andintermittently delivering an aqueous gel-forming substance and anaqueous gel-inducing substance to said conduits in response to said flowfor mixture with said water to form a solution of gelforming substanceand a solution of gel-inducing substance, respectively, which flows toand is selectively and intermittently discharged from said heads to forma fire extinguishing blanket of an aqueous gel material for goods storedin said space.

25. The method of claim 24 further comprising the step of separatelystoring said gel-forming and gel inducing substance before they aredelivered to said conduits, said gel-forming and said gel-inducingsubstances being selectively and intermittently released from saidseparate storage means into said water flowing through said conduits.

26. A method of fire protection comprising the steps of disposing aplurality of discharge heads in an elevated position in a space to beprotected from fire, normally maintaining said heads in a closedcondition, connecting said heads to a source of water by a singleconduit system, selectively opening each head automatically in responseto a predetermined fire condition in its vicinity to 'permit said waterto flow through said conduit system to said head, separately storing agelforming substance and a gel-inducing substance, and separately andintermittently injecting said gel-forming substance and saidgel-inducing substance into said conduit system in response to saidwater flow to form a solution of gel-forming substance and a solution of1 I S'IIATESEPATENT own I v Q CERTIFICATE v 0F CORRECTION PatentNo. 6 ad Siegtember 3, 1974 WILLIAM L. LIVINGSTON Inventofls) It is certifiedthat error appears in the above identified patent and that said LettersPatent are hereby corrected. as shown below:

In claims .14, 15, 16, and 17, the dependency which reads "12-" shouldread .3. f

Claim 15, column 9, line 22, chahge "sotrage" to read. -sto rage-.

Signed and sealed this 17th day of December 1974.

(SEAL) Attest:

McCOY M. GIBSON JR. c. MARSHALLI'HDANN Attesting Officer Cqmissioner' ofPatents

1. A fire extinguishing system comprising a plurality of normally closeddischarge heads, conduit means supporting said heads in an elevatedposition in a space to be protected from fire, said conduit meansconnecting said heads to a source of water and comprising a first groupof spaced parallel branch conduits for receiving one group of heads anda second group of spaced parallel branch conduits for receiving anothergroup of heads, means associated with each head for opening said head inresponse to a predetermined fire condition in its vicinity to permitsaid water to flow through said conduit means for discharge from saidheads, delivery means responsive to said flow for separately deliveringan aqueous gel-forming substance to said first group of branch conduitsand an aqueous gel-inducing substance to said second group of branchconduits, said gelforming substance and said gel-inducing substancemixing with said water to form a solution of gel-forming substance and asolution of gel-inducing substance which are delivered to said one groupof heads and said other group of heads, respectively, said first andsecond groups of branch conduits extending in an alternatingrelationship along said space and the position of the heads on eachbranch conduit being staggered Relative to the position of the heads onits adjacent conduits to mix said solutions upon their discharge fromsaid heads to form a fire extinguishing blanket of an aqueous gelmaterial for goods stored in said space.
 2. The system of claim 1wherein said means for opening said heads is adapted to open said headsin a manner to permit each head in said one group to discharge saidaqueous gel-forming substance at the same time a corresponding head insaid other group discharges said aqueous gel-inducing substance.
 3. Thesystem of claim 2 wherein said heads are adapted to discharge saidsubstances in a divergent spray pattern, with the spray pattern of eachhead in said one group of heads adapted to overlap the spray pattern ofa corresponding head in said other group of heads so that saidsubstances can mix at a predetermined vertical distance from said headsto form said blanket.
 4. The system of claim 3 further comprising meansfor separately storing said gel-forming substance and said gel-inducingsubstance, said delivery means further including means for separatelyreleasing said gel-forming and gel-inducing substances from said storagemeans to said first group of branch conduits and to said second group ofbranch conduits, respectively.
 5. The system of claim 4 wherein saidconduit means further comprises a first conduit connecting said sourceof water to said first group of branch conduits and a second conduit forconnecting said source of water to said second group of branch conduits,said releasing means further comprising means for injecting saidgel-forming substance and said gel-inducing substance into water flowingin said first and second conduits, respectively.
 6. The system of claim1 wherein said blanket flowingly envelopes said goods and substantiallycovers same.
 7. Te system of claim 1 wherein said gel-forming substanceis polyvinyl alcohol and said gel-inducing substance is borax.
 8. A fireextinguishing system comprising a first group of spaced parallelconduits and a second group of spaced parallel conduits extending in analternating relationship in an elevated position in a space to beprotected from fire, means connecting said conduits to a source ofwater, a plurality of normally closed discharge heads positionedsubstantially intermediate two adjacent branch conduits and connectedthereto, means associated with each head for opening said head inresponse to a predetermined fire condition in its vicinity to permitsaid water to flow through said conduit means to said heads, deliverymeans responsive to said flow for separately delivering an aqueousgel-forming substance to said first group of conduits and an aqueousgel-inducing substance to said second group of conduits for mixture withsaid water to form a solution of gel-forming substance and a solution ofgel-inducing substance, respectively, for delivery to each of saidheads, said heads being constructed and arranged to mix said solutionsand discharge same in the form of a fire extinguishing blanket of anaqueous gel material towards goods stored in said space.
 9. The systemof claim 8 further comprising means for separately storing saidgel-forming substance and said gel-inducing substance, said deliverymeans further including means for separately releasing said gel-formingand gel-inducing substances from said storage means to said first groupof spaced parallel conduits and said second group of spaced parallelconduits, respectively.
 10. The system of claim 9 wherein saidconnecting means comprises a first and second conduit respectivelyconnecting said first and said group of conduits to said source ofwater, said releasing means further comprising means for injectingadditives into water flowing in said first and second conduits to formsaid gel-forming substance and gel-inducing substance, respectively. 11.The system of claim 8 wherein said blanket flowingly envelopes saidgoods and substantially covers same.
 12. The system of claim 8 whereinsaid gel-forminG substance is polyvinyl alcohol and said gel-inducingsubstance is borax.
 13. A fire extinguishing system comprising aplurality of normally closed discharge heads disposed in an elevatedposition in a space to be protected from fire, conduit means connectingsaid heads to a source of water, means associated with each head foropening said head in response to a predetermined fire condition in itsvicinity to permit said water to flow through said conduit means to saidheads, delivery means responsive to said flow for selectively andintermittently delivering an aqueous gel-forming substance and anaqueous gel-inducing substance to said conduit means for mixture withsaid water to form a solution of gel-forming substance and a solution ofgel-inducing substance, respectively, for selective intermittentdischarge from each of said heads to form a fire extinguishing blanketof an aqueous gel material over goods stored in said space.
 14. Thesystem of claim 12 wherein said conduit means comprises a riserconnected to said source of water, a plurality of branch conduitsconnected to said heads, and a cross-main conduit connecting said riserto said branch conduits.
 15. The system of claim 12 further comprisingseparate storage means for said gel-forming and gel-inducing substance,said delivery means being adapted to selectively and intermittentlyrelease said gel-forming and said gel-inducing substances from saidseparate sotrage means into said water flowing through said conduitmeans.
 16. The system of claim 12 wherein said blanket flowinglyenvelopes said goods and substantially covers same.
 17. The system ofclaim 12 wherein said gel-forming substance is polyvinyl alcohol andsaid gel-inducing substance is borax.
 18. A method of fire protectioncomprising the steps of disposing a first group of conduits and a secondgroup of conduits in an alternating relationship in an elevated positionin a space to be protected from fire, connecting a first group ofnormally closed discharge heads to said first group of conduits,connecting a second group of normally closed discharge heads to saidsecond group of conduits with the position of the heads on each branchconduit being staggered relative to the position of the heads on itsadjacent conduits, connecting said conduits to a source of water,selectively opening each head in response to a predetermined firecondition in its vicinity to permit said water to flow through saidconduits for discharge from said heads, separately delivering an aqueousgel-forming substance to said first group of conduits and an aqueousgel-inducing substance to said second group of conduits in response tosaid flow, said gel-forming substance and said gel-inducing substancemixing with said water to form a solution of gel-forming substance insaid first group of conduits and a solution of gel-inducing substance insaid second group of conduits, which flows to and is discharged fromsaid first group of heads and said second group of heads, respectively,said solutions mixing upon their discharge from said heads to form afire extinguishing blanket of an aqueous gel material for goods storedin said space.
 19. The method of claim 18 wherein said heads are openedin a manner to permit each head in said one group to discharge saidaqueous gel-forming substance at the same time a corresponding head insaid other group discharges said aqueous gel-inducing substance.
 20. Themethod of claim 19 wherein said heads are adapted to discharge saidsubstances in a divergent spray pattern, with the spray pattern of eachhead in said one group of heads overlapping the spray pattern of acorresponding head in said other group of heads so that said substancescan mix at a predetermined vertical distance from said heads to formsaid blanket.
 21. The method of claim 18 further comprising the step ofseparately storing said gel-forming substance and said gel-inducingsubstance before they are delivered to said first group of branchconduits and said second group of branch conduits, respectively.
 22. Amethod of fire protection comprising the steps of supporting a first andsecond group of conduits in an elevated position in a space to beprotected from fire with the conduits of the first group extending in analternating relationship with the conduits of the second group,connecting said conduits to a source of water, connecting a plurality ofnormally closed discharge heads to said conduits with each head beingpositioned substantially intermediate two adjacent branch conduits andconnected thereto, selectively opening each head in response to apredetermined fire condition in its vicinity to permit said water toflow through said conduits to said heads, and separately delivering anaqueous gel-forming substance to said first group of conduits and anaqueous gel-inducing substance to said second group of conduits inresponse to said flow, said gel-forming substance and said gel-inducingsubstance mixing with said water to form a solution of gel-formingsubstance in said first group of conduits and solution of gel-inducingsubstance in said second group of conduits, said heads being constructedand arranged to mix said solutions and discharge same in the form of afire extinguishing blanket of an aqueous gel material for goods storedin said space.
 23. The method of claim 22 further comprising the step ofseparately storing said gel-forming substance and said gel-inducingsubstance before they are delivered to said first group of branchconduits and said second group of branch conduits, respectively.
 24. Amethod of fire protection comprising the steps of connecting a group ofnormally closed discharge heads to a plurality of spaced parallelconduits, connecting said conduits to a source of water, selectivelyopening each head in response to a predetermined fire condition in itsvicinity to permit said water to flow through said conduits fordischarge from said heads, and selectively and intermittently deliveringan aqueous gel-forming substance and an aqueous gel-inducing substanceto said conduits in response to said flow for mixture with said water toform a solution of gel-forming substance and a solution of gel-inducingsubstance, respectively, which flows to and is selectively andintermittently discharged from said heads to form a fire extinguishingblanket of an aqueous gel material for goods stored in said space. 25.The method of claim 24 further comprising the step of separately storingsaid gel-forming and gel-inducing substance before they are delivered tosaid conduits, said gel-forming and said gel-inducing substances beingselectively and intermittently released from said separate storage meansinto said water flowing through said conduits.
 26. A method of fireprotection comprising the steps of disposing a plurality of dischargeheads in an elevated position in a space to be protected from fire,normally maintaining said heads in a closed condition, connecting saidheads to a source of water by a single conduit system, selectivelyopening each head automatically in response to a predetermined firecondition in its vicinity to permit said water to flow through saidconduit system to said head, separately storing a gel-forming substanceand a gel-inducing substance, and separately and intermittentlyinjecting said gel-forming substance and said gel-inducing substanceinto said conduit system in response to said water flow to form asolution of gel-forming substance and a solution of gel-inducingsubstance, respectively, for discharge from said heads at predeterminedintervals, said solutions mixing to form a fire extinguishing blanket ofan aqueous gel material for goods stored in said blanket.